使用fastjson快速生成json字符串

为什么要用fastjson

如果手上有一个对象集合
要返回数据时拼json字符串很麻烦

示例代码

```go
package servlet;

import bean.Student;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.List;

@WebServlet("/student_list")
public class StudentList extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        // 说到
        resp.setHeader("Content-Type", "text/html;charset=utf-8");
        // 做到
        resp.setCharacterEncoding("utf-8");
        // 模拟得到对象集合
        List<Student> studentList = getStudentList();
        // 返回json数据给前端
        //   [{"name":"张三","age":16},{"name":"李四","age":22},{"name":"张三","age":16},]
        // json字符串
        String jsonStr = "";
        jsonStr += "[";
        for (Student s : studentList
        ) {
            String fmt = "{\"name\":\"%s\",\"age\":%s}";
            String d = String.format(fmt, s.getName(), s.getAge());  // {"name":"张三","age":16}
            jsonStr += d;
            jsonStr += ",";
        }
        jsonStr = jsonStr.substring(0, jsonStr.length() - 1);
        jsonStr += "]";

        System.out.println(jsonStr);

        // 返回数据
        PrintWriter writer = resp.getWriter();
        writer.write(jsonStr);
    }

    private List<Student> getStudentList() {
        // 模拟返回数据

        // 对象集合
        List<Student> studentList = new ArrayList<>();

        // 新建对象，设置属性
        Student xm = new Student();
        xm.setName("小明");
        xm.setAge(16);
        Student xh = new Student();
        xh.setName("小红");
        xh.setAge(26);

        // 把对象添加到集合中
        studentList.add(xm);
        studentList.add(xh);

        // 返回集合
        return studentList;


    }
}

使用fastjson一行代码解决问题

下载信息

文件名：

fastjson20220521